Two Dimensional Transport Induced Linear Magnetoresistance in Topological Insulator Bi$_{2}$Se$_{3}$ Nanoribbons*

Bulk Bi$_{2}$Se$_{3}$ has been proposed and confirmed as a type of three dimensional (3D) topological insulators (TI's) with a single Dirac cone for the surface state. Although the existence of topological surface state in Bi$_{2}$Se$_{3}$ has been established by surface sensitive techniques (ARPES, STM), the transport properties of two dimensional (2D) surface state in 3D TI's has been plagued by the dominating conductivity from bulk carriers. Here, we report the study of a novel linear magneto-resistance (MR) under perpendicular magnetic fields in Bi$_{2}$Se$_{3}$ nanoribbons, and show that this linear MR is purely due to 2D transport by angular dependence experiments. The 2D magneto-transport induced linear MR in Bi$_{2}$Se$_{3}$ nanoribbons is in agreement with the recently discovered linear MR from topological surface state in bulk Bi$_{2}$Te$_{3}$, and the MR of other gapless semiconductors and graphene. We further show that the linear MR of Bi$_{2}$Se$_{3}$ nanoribbons persists up to room temperature, underscoring the potential of exploiting TI's for room temperature magnetoelectronic applications. Reference: arXiv:1003.6099, arXiv:1101.2152